Light emitting device for display and light emitting package having the same

ABSTRACT

A light emitting device for a display including a first LED sub-unit, a second LED sub-unit disposed on the first LED sub-unit, and a third LED sub-unit disposed on the second LED sub-unit, in which the third LED sub-unit is configured to emit light having a shorter wavelength than that of light emitted from the first LED sub-unit, and to emit light having a longer wavelength than that of light emitted from the second LED sub-unit.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of U.S.Provisional Application No. 62/902,069, filed on Sep. 18, 2019, which ishereby incorporated by reference for all purposed as if fully set forthherein.

BACKGROUND Field

Exemplary embodiments of the invention relate generally to a lightemitting device for display and a light emitting package, and, morespecifically, to a light emitting device for a display having a stackedstructure of a plurality of LEDs and a light emitting package having thesame.

Discussion of the Background

As an inorganic light source, light emitting diodes have been used invarious technical fields including displays, vehicular lamps, generallighting, and the like. With various advantages of light emitting diodesover conventional light sources, such as longer lifespan, lower powerconsumption, and rapid response, light emitting diodes have beenreplacing conventional light sources.

Light emitting diodes have been used as backlight light sources indisplay apparatuses. However, LED displays that directly display imagesusing the light emitting diodes have been recently developed.

In general, a display apparatus realizes various colors through mixtureof blue, green, and red light. In order to display various images, thedisplay apparatus include pixels that each includes sub-pixelscorresponding to blue, green, and red light, respectively. As such, acolor of a certain pixel is determined based on the colors of thesub-pixels, and images can be displayed through combination of suchpixels.

Since LEDs can emit various colors depending upon materials thereof, itis possible to provide a display apparatus by arranging individual LEDchips emitting blue, green, and red light on a two-dimensional plane.However, when one LED chip is provided for each sub-pixel, the number ofLED chips may be increased, which may require excessive time for amounting process during manufacture.

In addition, when the sub-pixels are arranged on a two-dimensional planein the display apparatus, a relatively large area is occupied by onepixel that includes the sub-pixels for blue, green, and red light. Thus,an area of each LED chip should be reduced to arrange the sub-pixels ina restricted area. However, reduction in the sizes of the LED chipsmakes it difficult to mount the LED chips, as well as causing reductionin luminous areas of the LED chips.

Meanwhile, a display apparatus that realizes various colors needs toconsistently provide high-quality white light. For example, conventionalTVs use an RGB mixing ratio of 3:6:1 to realize the standard white lightof D65. More particularly, luminous intensity of red is higher than thatof blue, and luminous intensity of green is relatively the highest.However, in the conventional LED chips, a blue LED has relatively veryhigh luminous intensity compared to that of other LEDs, and thus, it isdifficult to match the RGB mixing ratio in the display apparatus usingLED chips.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Light emitting devices constructed according to exemplary embodiments ofthe invention are capable of increasing an area of each sub-pixel in arestricted pixel area and a display apparatus including the same.

Exemplary embodiments also provide a light emitting device for a displaythat is capable of reducing a time associated with a mounting processand a display apparatus including the same.

Exemplary embodiments further provide a light emitting device for adisplay that is capable of increasing production yield and a displayapparatus including the same.

Exemplary embodiments still provide a light emitting device and adisplay apparatus that facilitates controlling an RGB mixing ratio.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

A light emitting device for a display according to an exemplaryembodiment includes a first LED sub-unit, a second LED sub-unit disposedon the first LED sub-unit, and a third LED sub-unit disposed on thesecond LED sub-unit, in which the third LED sub-unit is configured toemit light having a shorter wavelength than that of light emitted fromthe first LED sub-unit, and to emit light having a longer wavelengththan that of light emitted from the second LED sub-unit.

The first, second, and third LED sub-units may be configured to emit redlight, blue light, and green light, respectively.

The first LED sub-unit may include a first light emitting stack, thesecond LED sub-unit may include a second light emitting stack, the thirdLED sub-unit may include a third light emitting stack, and each of thelight emitting stacks may include a first conductivity typesemiconductor layer, an active layer, and a second conductivity typesemiconductor layer.

The light emitting device may further include a substrate on which thefirst, second, and third LED sub-units are disposed, in which the thirdLED sub-unit may be disposed closer to the substrate than the first andsecond LED sub-units, and the substrate may have irregularities on anupper surface thereof.

The substrate may include a patterned sapphire substrate.

The first conductivity type semiconductor layer of the third LED stackmay be in contact with the upper surface of the substrate.

The light emitting device may further include a first bonding layerinterposed between the first LED sub-unit and the second LED sub-unit,and a second bonding layer interposed between the second LED sub-unitand the third LED sub-unit.

The light emitting device may further include a first connectionelectrode overlapping with at least one of the first, second, and thirdLED sub-units and electrically connected to at least one of the first,second, and third LED sub-units, in which the first connection electrodemay have a first side surface of a first length and a second sidesurface of a second length and opposing the first side surface, and adifference between the first length and the second length may be greaterthan a thickness of at least one of the LED sub-units.

The light emitting device may further include a protection layersurrounding at least a portion of the first connection electrode andexposing a side surface of the substrate.

The first side surface may face the outside of the light emittingdevice, the second side surface may face a center of the light emittingdevice, and the first length of the first side surface may be greaterthan the second length of the second side surface.

The protection layer may include an epoxy molding compound or polyimidefilm, and the protection layer may cover an upper surface of the firstLED sub-unit.

The light emitting device may further include a second connectionelectrode electrically connected to the first LED sub-unit, a thirdconnection electrode electrically connected to the second LED sub-unit,and a fourth connection electrode electrically connected to the thirdLED sub-unit, in which the first connection electrode may beelectrically connected to each of the first, second, and third LEDsub-units.

The lower surfaces of the first, second, third, and fourth connectionelectrodes may be larger than the respective upper surfaces.

At least one of the first, second, third, and fourth connectionelectrodes may overlap a side surface of each of the first, second,third, and fourth LED sub-units.

The first LED sub-unit may include a first conductivity typesemiconductor layer, an active layer, a second conductivity typesemiconductor layer, and an upper contact electrode in ohmic contactwith the first conductivity type semiconductor layer, the firstconductivity type semiconductor layer may include a recessed portion,and the upper contact electrode may be formed in the recessed portion ofthe first conductivity type semiconductor layer.

A light emitting package according to another exemplary embodimentincludes a circuit board, a light emitting device disposed on thecircuit board, and a molding layer covering the light emitting device,in which the light emitting device includes a first LED sub-unit, asecond LED sub-unit disposed on the first LED sub-unit, and a third LEDsub-unit disposed on the second LED sub-unit, the third LED sub-unit isconfigured to emit light having a shorter wavelength than that of lightemitted from the first LED sub-unit, and to emit light having a longerwavelength than that of light emitted from the second LED sub-unit.

The light emitting device may further include a substrate, the third LEDsub-unit may be disposed closer to the substrate than the first andsecond LED sub-units, and the substrate may have irregularities on anupper surface thereof.

The light emitting device may further include a plurality of connectionelectrodes disposed on the first, second, and third LED sub-units, and aprotection layer disposed between the connection electrodes, and theprotection layer and the molding layer may include different materialsfrom each other.

The first LED sub-unit may include a first conductivity typesemiconductor layer, an active layer, a second conductivity typesemiconductor layer, and an upper contact electrode in ohmic contactwith the first conductivity type semiconductor layer, the firstconductivity type semiconductor layer may include a recessed portion,and the upper contact electrode may be formed in the recessed portion ofthe first conductivity type semiconductor layer.

At least one of the connection electrodes may have a first side surfacewith a first length and a second side surface with a second length andopposing the first side surface, and a difference between the firstlength and second length may be at least 3 μm.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1A shows a schematic perspective view of a light emitting deviceaccording to an exemplary embodiment.

FIG. 1B is a schematic plan view of the light emitting device of FIG.1A.

FIG. 1C and FIG. 1D are schematic cross-sectional views taken alonglines A-A′ and B-B′ of FIG. 1B, respectively.

FIG. 1E is a SEM image of the light emitting device of FIG. 1A.

FIG. 2 is a schematic cross-sectional view of a light emitting stackedstructure according to an exemplary embodiment.

FIGS. 3A, 4A, 5A, 6A, 7A, and 8A are plan views illustrating a processof manufacturing the light emitting device of FIG. 1A according to anexemplary embodiment.

FIGS. 3B, 4B, 5B, 6B, 7B, and 8B are cross-sectional views taken alongline A-A′ of the corresponding plan views shown in FIGS. 3A, 4A, 5A, 6A,7A, and 8A according to an exemplary embodiment.

FIG. 9 is a schematic cross-sectional view of the light emitting deviceof FIG. 1A according to an exemplary embodiment.

FIGS. 10, 11, 12, and 13 are cross-sectional views schematicallyillustrating a process of manufacturing the light emitting device ofFIG. 1A according to an exemplary embodiment.

FIGS. 14, 15, 16A, and 17 are cross-sectional views schematicallyillustrating a process of manufacturing a light emitting packageaccording to an exemplary embodiment.

FIG. 16B is schematic plan view of the light emitting device of FIG.16A.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group consisting of X, Y, and Z” may be construed as Xonly, Y only, Z only, or any combination of two or more of X, Y, and Z,such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings. Hereinafter, a light emittingstacked structure, a light emitting device, or a light emitting packagemay include micro-LEDs, which may have a light emitting area of 10,000μm² or less as known in the art. However, the micro-LEDs are not limitedthereto, and may have a light emitting area of 4000 μm² or less, andfurther, 2500 μm² or less depending on applications.

FIG. 1A shows a schematic perspective view of a light emitting deviceaccording to an exemplary embodiment. FIG. 1B is a schematic plan viewof the light emitting device of FIG. 1A. FIG. 1C and FIG. 1D areschematic cross-sectional views taken along lines A-A′ and B-B′ of FIG.1B, respectively, and FIG. 1E is a SEM image of the light emittingdevice of FIG. 1A.

Referring to FIGS. 1A and 1B, a light emitting device 100 includes alight emitting stacked structure, a first connection electrode 20 ce, asecond connection electrode 30 ce, a third connection electrode 40 ce,and a fourth connection electrode 50 ce formed on the light emittingstacked structure, and a protection layer 90 surrounding the connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce. An array of light emittingdevices 100 may be formed on a substrate 11. The light emitting device100 illustrated in FIG. 1A shows a singularized one from the array, andthus, may be referred to as a light emitting device. Formation andsingularization of the light emitting devices 100 will be describedlater in more detail. In some exemplary embodiments, the light emittingdevice 100 including the light emitting stacked structure may be furtherprocessed to be formed into a light emitting package, which will also bedescribed later in more detail.

Referring to FIG. 1A and FIG. 1D, the light emitting device 100according to the illustrated exemplary embodiment may include a lightemitting stacked structure, and include a first LED sub-unit, a secondLED sub-unit, and a third LED sub-unit disposed on a substrate. Thefirst LED sub-unit may include a first light emitting stack 20, thesecond LED sub-unit may include a second light emitting stack 30, andthe third LED sub-unit may include a third light emitting stack 40. Thelight emitting stacked structure is exemplarily shown to include threelight emitting stacks 20, 30, and 40, but the inventive concepts are notlimited to a specific number of light emitting stacks. For example, insome exemplary embodiments, the light emitting stacked structure mayinclude two or more of light emitting stacks. Hereinafter, the lightemitting stacked structure will exemplarily be described as includingthree light emitting stacks 20, 30, and 40.

The substrate 11 may include a light-transmitting insulating material totransmit light. However, in some exemplary embodiments, the substrate 11may be translucent or partially transparent to transmit only lighthaving a specific wavelength or only a portion of light having aspecific wavelength. The substrate 11 may be a growth substrate on whichthe third light emitting stack 40 can be epitaxially grown, for example,a sapphire substrate. However, the substrate 11 is not limited to thesapphire substrate, and may include other various transparent insulatingmaterials. For example, the substrate 11 may include glass, quartz,silicon, an organic polymer, or an organic-inorganic composite material,such as silicon carbide (SiC), gallium nitride (GaN), indium galliumnitride (InGaN), aluminum gallium nitride (AlGaN), aluminum nitride(AlN), gallium oxide (Ga₂O₃), or a silicon substrate. In addition, thesubstrate 11 may include irregularities on an upper surface thereof, andfor example, may be a patterned sapphire substrate. By includingirregularities on the upper surface of the substrate 11, it is possibleto increase extraction efficiency of light generated in the third lightemitting stack 40 which is in contact with the substrate 11. Theirregularities of the substrate 11 may be included to selectivelyincrease luminous intensity of the third LED stack 40 compared to thoseof the first LED stack 20 and the second LED stack 30.

The first, second, and third light emitting stacks 20, 30, and 40 areconfigured to emit light toward the substrate 11. Accordingly, lightemitted from the first light emitting stack 20 may pass through thesecond and third light emitting stacks 30 and 40. In an exemplaryembodiment, the first, second, and third light emitting stacks 20, 30,and 40 may emit light having different peak wavelengths from oneanother. In general, a light emitting stack disposed relatively furtheraway from the substrate 11 emits light having a longer wavelength thanthat of light emitted from a light emitting stack disposed closer to thesubstrate 11, and thus, light loss may be reduced. However, the lightemitting device 100 according to the illustrated exemplary embodimentmay facilitate adjusting a color mixing ratio of the first, second, andthird light emitting stacks 20, 30, and 40, by forming the second LEDstack 30 to emit light having a shorter wavelength than that of lightemitted from the third LED stack 40. Accordingly, luminous intensity ofthe second LED stack 30 may be reduced, and luminous intensity of thethird LED stack 40 may be increased, and thus, luminous intensity ratiosof light emitted from the first, second, and third light emitting stacksmay be greatly changed. For example, the first light emitting stack 20may be configured to emit red light, the second light emitting stack 30may be configured to emit blue light, and the third light emitting stack40 may be configured to emit green light. In this case, luminousintensity of blue light may be relatively reduced, and luminousintensity of green light may be relatively increased, and thus, luminousintensity ratios of red, green, and blue light may be easily adjusted toapproach 3:6:1. Moreover, light emitting areas of the first, second, andthird LED stacks 20, 30, and 40 may be about 10000 μm² or less, andfurther, 4000 μm², furthermore, 2500 μm² or less. In addition, as thelight emitting stack is disposed closer to the substrate 11, theemitting area thereof may be larger. In this manner, the third LED stack40 that emits green light is disposed closest to the substrate 11, andthus, luminous intensity of green light may be further increased.

The first light emitting stack 20 includes a first conductivity typesemiconductor layer 21, an active layer 23, and a second conductivitytype semiconductor layer 25. According to an exemplary embodiment, thefirst light emitting stack 20 may include a semiconductor material, suchas AlGaAs, GaAsP, AlGaInP, and GaP that emits red light, but theinventive concepts are not limited thereto.

A first upper contact electrode 21 n may be disposed on the firstconductivity type semiconductor layer 21 and may be in ohmic contactwith the first conductivity type semiconductor layer 21. A first lowercontact electrode 25 p may be disposed under the second conductivitytype semiconductor layer 25. According to an exemplary embodiment, aportion of the first conductivity type semiconductor layer 21 may bepatterned, and the first upper contact electrode 21 n may be disposed ina patterned region of the first conductivity type semiconductor layer 21to increase an ohmic contact level. The first upper contact electrode 21n may have a single-layer structure or a multiple-layer structure, andmay include Al, Ti, Cr, Ni, Au, Ag, Sn, W, Cu, or an alloy thereof, suchas Au—Te alloy or Au—Ge alloy, but the inventive concepts are notlimited thereto. In an exemplary embodiment, the first upper contactelectrode 21 n may have a thickness of about 100 nm, and may includemetal having high reflectivity to increase light emission efficiency ina downward direction toward the substrate 11.

The second light emitting stack 30 includes a first conductivity typesemiconductor layer 31, an active layer 33, and a second conductivitytype semiconductor layer 35. According to an exemplary embodiment, thesecond light emitting stack 30 may include a semiconductor material,such as GaN, InGaN, ZnSe that emits blue light, but the inventiveconcepts are not limited thereto. A second lower contact electrode 35 pis disposed under the second conductivity type semiconductor layer 35 ofthe second light emitting stack 30.

The third light emitting stack 40 includes a first conductivity typesemiconductor layer 41, an active layer 43, and a second conductivitytype semiconductor layer 45. According to an exemplary embodiment, thethird light emitting stack 40 may include a semiconductor material, suchas GaN, InGaN, GaP, AlGaInP, AlGaP, or the like that emits green light.A third lower contact electrode 45 p is disposed on the secondconductivity type semiconductor layer 45 of the third light emittingstack 40.

According to an exemplary embodiment, each of the first conductivitytype semiconductor layers 21, 31, and 41 and the second conductivitytype semiconductor layers 25, 35, and 45 of the first, second, and thirdlight emitting stacks 20, 30, and 40 may have a single-layer structureor a multiple-layer structure, and, in some exemplary embodiments, mayinclude a superlattice layer. Moreover, the active layers 23, 33, and 43of the first, second, and third light emitting stacks 20, 30, and 40 mayhave a single-quantum well structure or a multiple-quantum wellstructure.

Each of the first, second, and third lower contact electrodes 25 p, 35p, and 45 p may include a transparent conductive material that transmitslight. For example, the lower contact electrodes 25 p, 35 p, and 45 pmay include transparent conductive oxide (TCO), such as SnO, InO₂, ZnO,ITO, ITZO, or the like, without being limited thereto.

A first adhesive layer 61 is disposed between the first light emittingstack 20 and the second light emitting stack 30, and a second adhesivelayer 63 is disposed between the second light emitting stack 30 and thethird light emitting stack 40. The first and second adhesive layers 61and 63 may include a non-conductive material that transmits light. Forexample, the first and second adhesive layers 61 and 63 may include anoptically clear adhesive (OCA), which epoxy, polyimide, SUB,spin-on-glass (SOG), benzocyclobutene (BCB), but the inventive conceptsare not limited thereto.

According to the illustrated exemplary embodiment, a first insulationlayer 81 and a second insulation layer 83 are disposed on at least aportion of side surfaces of the first, second, and third light emittingstacks 20, 30, and 40. At least one of the first and second insulationlayers 81 and 83 may include various organic or inorganic insulatingmaterials, such as polyimide, SiO₂, SiN_(x), Al₂O₃, or the like. Forexample, at least one of the first and second insulation layers 81 and83 may include a distributed Bragg reflector (DBR). As another example,at least one of the first and second insulation layers 81 and 83 mayinclude a black organic polymer. In some exemplary embodiments, anelectrically floating metal reflection layer may be disposed on thefirst and second insulation layers 81 and 83 and may reflect lightemitted from the light emitting stacks 20, 30, and 40 toward thesubstrate 11. In some exemplary embodiments, at least one of the firstand second insulation layers 81 and 83 may have a single-layer structureor a multiple-layer structure formed of two or more insulation layershaving different refractive indices.

According to an exemplary embodiment, each of the first, second, andthird light emitting stacks 20, 30, and 40 may be driven independently.More specifically, a common voltage may be applied to one of the firstand second conductivity type semiconductor layers of each of the lightemitting stacks, and an individual emission signal may be applied to theremaining one of the first and second conductivity type semiconductorlayers of each of the light emitting stacks. For example, according toan exemplary embodiment, the first conductivity type semiconductorlayers 21, 31, and 41 of each of the light emitting stacks 20, 30, and40 may be n-type, and the second conductivity type semiconductor layers25, 35, and 45 of each of the light emitting stacks 20, 30, and 40 maybe p-type. In this case, the third light emitting stack 40 may have astacked sequence that is opposite to those of the first light emittingstack 20 and the second light emitting stack 30. More particularly, thep-type semiconductor layer 45 may be disposed over the active layer 43to simplify processes of manufacturing the light emitting device 100.Hereinafter, the first conductivity type and the second conductivitytype semiconductor layers may also be referred as n-type and p-type,respectively. However, in some exemplary embodiments, n-type and p-typemay be reversed.

Each of the first, second, and third lower contact electrodes 25 p, 35p, and 45 p that are connected to the p-type semiconductor layers 25,35, and 45 of the light emitting stacks, respectively, may beelectrically connected to a fourth contact 50C. The fourth contact 50Cmay be connected to the fourth connection electrode 50 ce to receive acommon voltage from the outside. Meanwhile, the n-type semiconductorlayers 21, 31, and 41 of the light emitting stacks may be connected to afirst contact 20C, a second contact 30C, and a third contact 40C,respectively, and may receive corresponding emission signals through theconnection electrodes 20 ce, 30 ce, and 40 ce, respectively. In thismanner, each of the first, second, and third light emitting stacks 20,30, and 40 may be driven independently from one another while having acommon p-type light emitting stacked structure.

The light emitting device 100 according to the illustrated exemplaryembodiment has the common p-type structure, but the inventive conceptsare not limited thereto. For example, in some exemplary embodiments, thefirst conductivity type semiconductor layers 21, 31, and 41 of each ofthe light emitting stacks may be p-type, and the second conductivitytype semiconductor layer 25, 35, and 45 of each of the light emittingstacks may be n-type, and a common n-type light emitting stackedstructure may be formed. In addition, in some exemplary embodiments, thestacked sequence of each of the light emitting stacks is not limited tothat shown in the drawing, but may be variously modified. Hereinafter,the light emitting device 100 will exemplarily be described as havingthe common n-type light emitting stacked structure.

According to the illustrated exemplary embodiment, the first contact 20Cincludes a first pad 20 pd and a first bump electrode 20 bp electricallyconnected to the first pad 20 pd. The first pad 20 pd is disposed on thefirst upper contact electrode 21 n of the first light emitting stack 20and is connected to the first upper contact electrode 21 n through afirst contact hole 20CH defined through the first insulation layer 81.At least a portion of the first bump electrode 20 bp may be overlappedwith the first pad 20 pd, and the first bump electrode 20 bp isconnected to the first pad 20 pd through a first through hole 20 ct withthe second insulation layer 83 interposed therebetween in the overlappedregion between the first bump electrode 20 bp and the first pad 20 pd.In this case, the first pad 20 pd and the first bump electrode 20 bp mayhave substantially the same shape and overlap each other, but theinventive concepts are not limited thereto.

The second contact 30C includes a second pad 30 pd and a second bumpelectrode 30 bp electrically connected to the second pad 30 pd. Thesecond pad 30 pd is disposed on the first conductivity typesemiconductor layer 31 of the second light emitting stack 30, and isconnected to the first conductivity type semiconductor layer 31 througha second contact hole 30CH defined through the first insulation layer81. A portion of the second bump electrode 30 bp may be overlapped withthe second pad 30 pd. The second bump electrode 30 bp may be connectedto the second pad 30 pd through a second through hole 30 ct with thesecond insulation layer 83 interposed therebetween in the overlappedregion between the second bump electrode 30 bp and the second pad 30 pd.

The third contact 40C includes a third pad 40 pd and a third bumpelectrode 40 bp electrically connected to the third pad 40 pd. The thirdpad 40 pd is disposed on the first conductivity type semiconductor layer41 of the third light emitting stack 40, and is connected to the firstconductivity type semiconductor layer 41 through a third contact hole40CH defined through the first insulation layer 81. A portion of thethird bump electrode 40 bp may be overlapped with the third pad 40 pd.The third bump electrode 40 bp may be connected to the third pad 40 pdthrough a third through hole 40 ct with the second insulation layer 83interposed therebetween in the overlapped region between the third bumpelectrode 40 bp and the third pad 40 pd.

The fourth contact 50C includes a fourth pad 50 pd and a fourth bumpelectrode 50 bp electrically connected to the fourth pad 50 pd. Thefourth pad 50 pd is connected to the second conductivity typesemiconductor layers 25, 35, and 45 of the first, second, and thirdlight emitting stacks 20, 30, and 40 through a first sub-contact hole50CHa and a second sub-contact 50CHb defined on the first, second andthird lower contact electrodes 25 p, 35 p and 45 p of the first, secondand third light emitting stacks 20, 30 and 40. In particular, the fourthpad 50 pd is connected to the first lower contact electrode 25 p throughthe second sub-contact hole 50CHb, and is connected to the second andthird lower contact electrodes 35 p and 45 p through the firstsub-contact hole 50CHa. In this manner, the fourth pad 50 pd may beconnected to the second and third lower contact electrodes 35 p and 45 pthrough a single first sub-contact hole 50CHa, so that the process ofmanufacturing the light emitting device 100 may be simplified and anarea occupied by the contact holes in the light emitting device 100 maybe reduced. At least a portion of the fourth bump electrode 50 bp may beoverlapped with the fourth pad 50 pd. The fourth bump electrode 50 bpmay be connected to the fourth pad 50 pd through a fourth through hole50 ct with the second insulation layer 83 interposed therebetween in theoverlapped region between the fourth bump electrode 50 bp and the fourthpad 50 pd.

The inventive concepts are not limited to a specific structures of thecontacts 20C, 30C, 40C, and 50C. For example, in some exemplaryembodiments, the bump electrode 20 bp, 30 bp, 40 bp, or 50 bp may beomitted from at least one of the contacts 20C, 30C, 40C, and 50C. Inthis case, the pads 20 pd, 30 pd, 40 pd, and 50 pd of the contacts 20C,30C, 40C, and 50C may be connected to respective connection electrodes20 ce, 30 ce, 40 ce, and 50 ce. In other exemplary embodiments, the bumpelectrodes 20 bp, 30 bp, 40 bp, and 50 bp may be omitted from each ofthe contacts 20C, 30C, 40C, and 50C, and the pads 20 pd, 30 pd, 40 pd,and 50 pd of the contacts 20C, 30C, 40C, and 50C may be directlyconnected to the corresponding connection electrodes 20 ce, 30 ce, 40ce, and 50 ce.

According to an exemplary embodiment, the first, second, third, andfourth contacts 20C, 30C, 40C, and 50C may be formed at variouslocations. For example, when the light emitting device 100 issubstantially rectangular as shown in the drawing, the first, second,third, and fourth contacts 20C, 30C, 40C, and 50C may be disposed aroundeach corner of the rectangular shape. However, the inventive conceptsare not limited thereto, and, in some exemplary embodiments, the lightemitting device 100 may be formed to have various shapes, and the first,second, third, and fourth contacts 20C, 30C, 40C, and 50C may be formedat different locations depending on the shape of the light emittingdevice.

The first, second, third, and fourth pads 20 pd, 30 pd, 40 pd, and 50 pdare spaced apart and insulated from one another. In addition, the first,second, third, and fourth bump electrodes 20 bp, 30 bp, 40 bp, and 50 bpare spaced apart and insulated from one another. According to anexemplary embodiment, each of the first, second, third, and fourth bumpelectrodes 20 bp, 30 bp, 40 bp, and 50 bp may cover at least a portionof side surfaces of the first, second, and third light emitting stacks20, 30, and 40. In this manner, heat generated from the first, second,and third light emitting stacks 20, 30, and 40 may be easily dissipated.

According to the illustrated exemplary embodiment, each of theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may have asubstantially elongated shape that protrudes from the substrate 11. Theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may include metal,such as Cu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag, or an alloy thereof, but theinventive concepts are not limited thereto. For example, each of theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may include two ormore metals or a plurality of different metal layers to reduce stressfrom the elongated shape of the connection electrodes 20 ce, 30 ce, 40ce, and 50 ce. In another exemplary embodiment, when the connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce contain Cu, an additionalmetal may be deposited or plated to inhibit oxidation of Cu. In someexemplary embodiments, when the connection electrodes 20 ce, 30 ce, 40ce, and 50 ce include Cu/Ni/Sn, Cu may prevent Sn from permeating intothe light emitting stacked structure. In some exemplary embodiments, theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may include a seedlayer for forming a metal layer in a plating process, which will bedescribed later.

As shown in the drawings, each of the connection electrodes 20 ce, 30ce, 40 ce, and 50 ce may have a substantially flat upper surface,thereby facilitating electrical connection between external lines (whichwill be described later) or electrodes and the light emitting stackedstructure. According to the illustrated exemplary embodiment, when thelight emitting device 100 includes micro LEDs having a surface area ofabout 10,000 μm² or less as known in the art, or include micro LEDshaving a surface area of about 4,000 μm² or about 2,500 μm² or less, theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may be overlappedwith at least a portion of one of the first, second, and third lightemitting stacks 20, 30, and 40 as shown in the drawing. Morespecifically, the connection electrodes 20 ce, 30 ce, 40 ce, and 50 cemay be overlapped with at least one step that is formed on the sidesurface of the light emitting stacked structure. As such, since an areaof a lower surface of the connection electrode is greater than that ofan upper surface thereof, a larger contact area may be formed betweenthe connection electrode 20 ce, 30 ce, 40 ce, and 50 ce and the lightemitting stacked structure. Accordingly, the connection electrodes 20ce, 30 ce, 40 ce, and 50 ce may be more stably formed on the lightemitting stacked structure than those in a conventional light emittingdevice. For example, lengths L1, L2, L3, and L4 of one side surface thatfaces the outside of the connection electrodes 20 ce, 30 ce, 40 ce, and50 ce may be different from lengths L1′, L2′, L3′, and L4′ of one sidesurface that faces toward a center of the light emitting device 100.More specifically, the length of one side surface of the connectionelectrode that faces the outside may be greater than that of anotherside surface that faces the center of the light emitting device 100. Forexample, a difference in lengths L and L′ of two surfaces opposite toeach other may be greater than a thickness (or height) of one of thelight emitting stacks 20, 30, and 40. In this manner, the structure ofthe light emitting device 100 may be strengthened with a larger contactarea between the connection electrodes 20 ce, 30 ce, 40 ce, and 50 ceand the light emitting stacked structure. In addition, since theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may be overlappedwith at least one step that is formed on the side surface of the lightemitting stacked structure, heat generated in the light emitting stackedstructure may be dissipated to the outside more efficiently.

According to an exemplary embodiment, a difference between the lengthL1, L2, L3 or L4 of one side surface of the connection electrode thatfaces the outside and the lengths L1′, L2′ L3′, and L4′ of the anotherside surface that faces the center of the light emitting device 100 maybe about 3 μm. In this case, the light emitting stacked structure may beformed thinly, and in particular, the first light emitting stack 20 mayhave a thickness of about 1 μm, the second light emitting stack 30 mayhave a thickness of about 0.7 μm, the third light emitting stack 40 mayhave a thickness of about 0.7 μm, and each of the first and secondadhesive layers may have a thickness of about 0.2 μm to about 0.3 μm,but the inventive concepts are not limited thereto. According to anotherexemplary embodiment, a difference between the length L1, L2, L3 or L4of one side surface of the connection electrode that faces to theoutside and the lengths L1′, L2′ L3′, and L4′ of the another sidesurface that faces the center of the light emitting device 100 may beabout 10 μm to about 16 μm. In this case, the light emitting stackedstructure may be formed relatively thick and has more stable structure,and in particular, the first light emitting stack 20 may have athickness of about 4 μm to about 5 μm, the second light emitting stack30 may have a thickness of about 3 μm, the third light emitting stack 40may have a thickness of about 3 μm, and each of the first and secondadhesive layers may have a thickness of about 0.3 μm, but the inventiveconcepts are not limited thereto. According to another exemplaryembodiment, a difference between the length L1, L2, L3 or L4 of one sidesurface of the connection electrode that faces to the outside and thelengths L1′, L2′ L3′, and L4′ of the another side surface that faces thecenter of the light emitting device 100 may be about 25% of a length ofa largest side surface. However, the inventive concepts are not limitedto a particular difference in lengths between the two surfaces of theconnection electrode opposite to each other, and the difference inlengths between the two surfaces opposite to each other may be changed.

In some exemplary embodiments, at least one of the connection electrodes20 ce, 30 ce, 40 ce, and 50 ce may be overlapped with the side surfaceof each of the light emitting stacks 20, 30, and 40, and thus, the lightemitting stacks 20, 30, and 40 may efficiently dissipate heat that isgenerated inside thereof. Further, when the connection electrodes 20 ce,30 ce, 40 ce, and 50 ce include a reflective material such as metal, theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may reflect lightthat is emitted from at least one or more of the light emitting stacks20, 30, and 40, and thus, luminous efficiency may be improved.

In general, during the manufacturing process, an array of a plurality oflight emitting devices is formed on a substrate. The substrate is cutalong a scribing line to singularize (separate) each of the lightemitting devices, and the light emitting device may be transferred toanother substrate or a tape using various transfer techniques forfurther processing of the light emitting devices, such as packaging. Inthis case, when the light emitting device includes connection electrodessuch as metal bumps or pillars protruding outward from the lightemitting structure, due to the structure of the light emitting deviceexposing the connection electrodes to the outside, during a subsequentprocess, for example, a transfer stage, various problems may occur. Inaddition, when the light emitting device contains micro-LEDs with asurface area of about 10,000 μm² or less, of about 4,000 μm² or less, orabout 2,500 μm² or less, depending on the application, handling of thelight emitting device may be more difficult due to a small form factor.

For example, when the connection electrode has a substantially elongatedshape such as a rod, transferring the light emitting device using aconventional vacuum method may become difficult because the lightemitting device may not have a sufficient suction area due to theprotruding structure of the connection electrode. In addition, theexposed connection electrode may be directly affected by variousstresses during a subsequent process, such as when the connectionelectrode contacts a manufacturing apparatus, which may damage thestructure of the light emitting device. As another example, when thelight emitting device is transferred by attaching an adhesive tape onthe upper surface of the light emitting device (for example, a surfaceopposite to the substrate), a contact area between the light emittingdevice and the adhesive tape may be limited to the upper surface of theconnection electrode. In this case, contrary to a case when the adhesivetape is attached to the lower surface of the light emitting device, suchas the substrate, an adhesive force of the light emitting device to theadhesive tape may be weakened, and the light emitting device may beundesirably separated from the adhesive tape while transferring thelight emitting device. As still another example, when transferring thelight emitting device using a conventional pick-and-place method, adischarge pin may directly contact a portion of the light emittingdevice disposed between connection pins, and thus, an upper structure ofthe light emitting structure may be damaged. In particular, thedischarge pin may hit the center of the light emitting device, and causephysical damage to an upper light emitting stack of the light emittingdevice. This impact on the light emitting device by the discharge pin isshown in FIG. 1E, in which the center of the light emitting device 100is pressed by the discharge pin.

According to an exemplary embodiment, the protection layer 90 may beformed on the light emitting stacked structure. More specifically, asshown in FIG. 1A, the protection layer 90 may be formed between theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce to cover at leastthe side surface of the light emitting stacked structure. According tothe illustrated exemplary embodiment, the protection layer 90 may exposeside surfaces of the substrate 11, the first and second insulationlayers 81 and 83, and a portion of the third light emitting stack 40.The protection layer 90 may be formed to be substantially flush with theupper surfaces of the connection electrodes 20 ce, 30 ce, 40 ce, and 50ce, and may include an epoxy molding compound (EMC), which may be formedin various colors, such as black, white, or transparent. However, theinventive concepts are not limited thereto. For example, in someexemplary embodiments, the protection layer 90 may include polyimide(PID), and in this case, PID may be provided as a dry film rather than aliquid type to increase flatness when PID is applied to the lightemitting stacked structure. In some exemplary embodiments, theprotection layer 90 may include a photosensitive substance. In thismanner, the protection layer 90 may provide a sufficient contact area tothe light emitting device 100 to facilitate handling during thesubsequent transfer step, as well as protecting the light emittingstructure from external impacts that may be applied during subsequentprocesses. In addition, the protection layer 90 may prevent lightleakage from the side surface of the light emitting device 100 toprevent or at least to suppress interference of light emitted from anadjacent light emitting device 100.

FIG. 2 is a schematic cross-sectional view of a light emitting stackedstructure according to an exemplary embodiment. Since the light emittingstacked structure according to the illustrated exemplary embodiment issubstantially the same as that included in the above-described lightemitting device 100, repeated descriptions of substantially the sameelements will be omitted to avoid redundancy.

Referring to FIG. 2, first, second, and third lower contact electrodes25 p, 35 p, and 45 p according to an exemplary embodiment may beconnected to a common line to which a common voltage Sc is applied.Emission signal lines SR, SG, and SB may be connected to the firstconductivity type semiconductor layers 21, 31, and 41 of the first,second, and third light emitting stacks 20, 30, and 40, respectively.The emission signal line is connected to the first conductivity typesemiconductor layer 21 of the first light emitting stack 20 through afirst upper contact electrode 21 n. In the illustrated exemplaryembodiment, the common voltage Sc is applied to the first, second, andthird lower contact electrodes 25 p, 35 p, and 45 p through the commonline, and the emission signals are applied to the first conductivitytype semiconductor layers 21, 31, and 41 of the first, second, and thirdlight emitting stacks 20, 30, and 40 through the emission signal lines,respectively. In this manner, the first, second, and third lightemitting stacks 20, 30, and 40 may be individually controlled toselectively emit light.

FIG. 2 exemplarily shows the light emitting stacked structure having thep-common structure, but the inventive concepts are not limited thereto.For example, in some exemplary embodiments, the common voltage Sc may beapplied to the first conductivity type (or n-type) semiconductor layers21, 31 and 41 of the first, second and third light emitting stacks 20,30 and 40, and the emission signal may be applied to the secondconductivity type (or p-type) semiconductor layers 25, 35, and 45 of thefirst, second, and third light emitting stacks 20, 30, and 40.

The light emitting stacked structure according to an exemplaryembodiment may display light having various colors according to anoperating state of each of the light emitting stacks 20, 30, and 40,whereas conventional light emitting devices may display a variety ofcolors in a combination of multiple light emitting cells that emit lightof a single color. More specifically, conventional light emittingdevices generally include light emitting cells spaced apart from oneanother along a two-dimensional plane and emitting light of differentcolors, for example, red, green, and blue, respectively, to realize afull color display. As such, a relatively large area may be occupied byconventional light emitting cells. However, the light emitting stackedstructure according to an exemplary embodiment may emit light havingdifferent colors by stacking a plurality of light emitting stacks 20,30, and 40. In this manner, the light emitting stacked structure mayprovide a high level of integration and realize full color displaythrough a smaller area than that of the conventional light emittingapparatus.

In addition, when the light emitting devices 100 are mounted on anothersubstrate to manufacture a display apparatus, the number of devices tobe mounted may be significantly reduced as compared to the conventionallight emitting device. More particularly, when hundreds of thousands ormillions of pixels are formed in one display apparatus, manufacturing ofthe display apparatus using the light emitting device 100 may besubstantially simplified.

According to an exemplary embodiment, the light emitting stackedstructure may further include various additional elements to improvepurity and efficiency of light emitted therefrom. For example, in someexemplary embodiments, a wavelength pass filter may be disposed betweenthe light emitting stacks. In some exemplary embodiments, anirregularity portion may be formed on a light emission surface of atleast one of the light emitting stacks to balance brightness of lightbetween the light emitting stacks. For example, luminous intensity ofgreen light needs to be increased to make the RGB mixing ratio close to3:6:1. As such, irregularities may be formed on the surface of thesubstrate 11 as described above.

Hereinafter, a method of forming the light emitting device 100 accordingto an exemplary embodiment will be described with reference to theaccompanying drawings.

FIGS. 3A, 4A, 5A, 6A, 7A, and 8A are plan views illustrating processesof manufacturing the light emitting device of FIG. 1A according to anexemplary embodiment. FIGS. 3B, 4B, 5B, 6B, 7B, and 8B arecross-sectional views taken along line A-A′ of the corresponding planviews shown in FIGS. 3A, 4A, 5A, 6A, 7A, and 8A according to anexemplary embodiment. FIG. 9 is a schematic cross-sectional view of thelight emitting device of FIG. 1A according to an exemplary embodiment.FIGS. 10, 11, 12, and 13 are cross-sectional views schematically showingprocesses of manufacturing the light emitting device of FIG. 1Aaccording to an exemplary embodiment.

Referring back to FIG. 2, the first conductivity type semiconductorlayer 41, the third active layer 43, and the second conductivity typesemiconductor layer 45 of the third light emitting stack 40 may besequentially grown on the substrate 11 by, for example, a metal organicchemical vapor deposition (MOCVD) method or a molecular beam epitaxy(MBE) method. The substrate 11 may include an irregularity pattern on anupper surface thereof, and may be, for example, a patterned sapphiresubstrate. The third lower contact electrode 45 p may be formed on thethird p-type semiconductor layer 45 by, for example, a physical vapordeposition or chemical vapor deposition method, and may includetransparent conductive oxide (TCO), such as SnO, InO₂, ZnO, ITO, ITZO,or the like. When the third light emitting stack 40 emits green lightaccording to an exemplary embodiment, the substrate 11 may include Al₂O₃(for example, a sapphire substrate), and the third lower contactelectrode 45 p may include transparent conductive oxide (TCO), such astin oxide. The first and second light emitting stacks 20 and 30 may besimilarly formed by sequentially growing the first conductivity typesemiconductor layer, the active layer, and the second conductivity typesemiconductor layer on a temporary substrate, respectively. The lowercontact electrodes including transparent conductive oxide (TCO) may beformed by, for example, a physical vapor deposition or chemical vapordeposition method on the second conductivity type semiconductor layer,respectively. In addition, the first and second light emitting stacks 20and 30 may be coupled to each other with the first adhesive layer 61interposed therebetween, and at least one of the temporary substrates ofthe first and second light emitting stacks 20 and 30 may be removed by alaser lift-off process, a chemical process, a mechanical process, or thelike. The first and second light emitting stacks 20 and 30 may becoupled to the third light emitting stack 40 with the second adhesivelayer 63 therebetween, and the remaining one of the temporary substratesof the first and second light emitting stacks 20 and 30 may be removedby a laser lift-off process, a chemical process, a mechanical process,or the like.

Referring to FIGS. 3A and 3B, various portions of each of the first,second, and third light emitting stacks 20, 30, and 40 may be patternedthrough an etching process or the like to expose portion of a firstconductivity type semiconductor layer 21, a first lower contactelectrode 25 p, a first conductivity type semiconductor layer 31, asecond lower contact electrode 35 p, a third lower contact electrode 45p, and a first conductivity type semiconductor layer 41. According tothe illustrated exemplary embodiment, the first light emitting stack 20has the smallest area among the light emitting stacks 20, 30, and 40.The third light emitting stack 40 may have the largest area among thelight emitting stacks 20, 30, and 40, and thus, luminous intensity ofthe third light emitting stack 40 may be relatively increased. However,the inventive concepts are not particularly limited to the relativesizes of the light emitting stacks 20, 30, and 40.

Referring to FIGS. 4A and 4B, a portion of an upper surface of the firstconductivity type semiconductor layer 21 of the first light emittingstack 20 may be patterned through wet etching to form a first uppercontact electrode 21 n thereon. As described above, the first uppercontact electrode 21 n may be formed to have the thickness of about 100nm in the patterned region of the first conductivity type semiconductorlayer 21, for example, which may improve an ohmic contact therebetween.

Referring to FIGS. 5A and 5B, a first insulation layer 81 may be formedto cover the light emitting stacks 20, 30, and 40, and a portion of thefirst insulation layer 81 may be removed to form first, second, third,and fourth contact holes 20CH, 30CH, 40CH, and 50CH. The first contacthole 20CH is defined on the first n-type contact electrode 21 n toexpose a portion of the first n-type contact electrode 21 n.

The second contact hole 30CH may expose a portion of the firstconductivity type semiconductor layer 31 of the second light emittingstack 30. The third contact hole 40CH may expose a portion of the firstconductivity type semiconductor layer 41 of the third light emittingstack 40. The fourth contact hole 50CH may expose portions of the first,second, and third lower contact electrodes 21 p, 31 p, and 41 p. Thefourth contact hole 50CH may include a first sub-contact hole 50CHaexposing a portion of the first lower contact electrode 25 p and asecond sub-contact hole 50CHb exposing the second and third lowercontact electrodes 35 p and 45 p. However, in some exemplaryembodiments, a single first sub-contact hole CH may expose each of thefirst, second, and third lower contact electrodes 21 p, 31 p, and 41 p.

Referring to FIGS. 6A and 6B, first, second, third, and fourth pads 20pd, 30 pd, 40 pd, and 50 pd are formed on the first insulation layer 81which is formed with the first, second, third, and fourth contact holes20CH, 30CH, 40CH, and 50CH. The first, second, third, and fourth pads 20pd, 30 pd, 40 pd, and 50 pd may be formed, for example, by forming aconductive layer on a substantially entire surface of the substrate 11,and patterning the conductive layer using a photolithography process.

The first pad 20 pd may be formed to be overlapped with a region wherethe first contact hole 20CH is formed, and the first pad 20 pd may beconnected to the first upper contact electrode 21 n of the first lightemitting stack 20 through the first contact hole 20CH. The second pad 30pd may be formed to be overlapped with a region where the second contacthole 30CH is formed, and the second pad 30 pd may be connected to thefirst conductivity type semiconductor layer 31 of the second lightemitting stack 30 through the second contact hole 30CH. The third pad 40pd may be formed to be overlapped with a region where the third contacthole 40CH is formed, and the third pad 40 pd may be connected to thefirst conductivity type semiconductor layer 41 of the third lightemitting stack 40 through the third contact hole 40CH. The fourth pad 50pd is formed to be overlapped with a region where the fourth contacthole 50CH is formed, particularly a region where the first and secondsub-contact holes 50CHa and 50CHb are formed, and the fourth pad 50 pdmay be connected to the lower contact electrodes 25 p, 35 p, and 45 p ofthe first, second, and third light emitting stacks 20, 30, and 40through the first and second sub-contact holes 50CHa and 50CHb.

Referring to FIGS. 7A and 7B, a second insulation layer 83 may be formedon the first insulation layer 81. The second insulation layer 83 mayinclude silicon oxide and/or silicon nitride. However, the inventiveconcepts are not limited thereto, and, in some exemplary embodiments,the first and second insulation layers 81 and 83 may include inorganicmaterials. Subsequently, the second insulation layer 83 may be patternedto form first, second, third, and fourth through holes 20 ct, 30 ct, 40ct, and 50 ct therein.

The first through hole 20 ct formed on the first pad 20 pd exposes aportion of the first pad 20 pd. The second through hole 30 ct formed onthe second pad 30 pd exposes a portion of the second pad 30 pd. Thethird through hole 40 ct formed on the third pad 40 pd exposes a portionof the third pad 40 pd. The fourth through hole 50 ct formed on thefourth pad 50 pd exposes a portion of the fourth pad 50 pd. In theillustrated exemplary embodiment, the first, second, third, and fourththrough holes 20 ct, 30 ct, 40 ct, and 50 ct may be defined withinregions where the first, second, third, and fourth pads 20 pd, 30 pd, 40pd, and 50 pd are formed, respectively.

Referring to FIGS. 8A and 8B, first, second, third and fourth bumpelectrodes 20 bp, 30 bp, 40 bp, and 50 bp are formed on the secondinsulation layer 83 on which the first, second, third and fourth throughholes 20 ct, 30 ct, 40 ct, and 50 ct are formed. The first bumpelectrode 20 bp may be formed to be overlapped with a region where thefirst through hole 20 ct is formed, and the first bump electrode 20 bpmay be connected to the first pad 20 pd through the first through hole20 ct. The second bump electrode 30 bp may be formed to be overlappedwith a region where the second through hole 30 ct is formed, and thesecond bump electrode 30 bp may be connected to the second pad 30 pdthrough the second through hole 30 ct. The third bump electrode 40 bpmay be formed to be overlapped with a region where the third throughhole 40 ct is formed, and the third bump electrode 40 bp may beconnected to the third pad 40 bp through the third through hole 40 ct.The fourth bump electrode 50 bp may be formed to be overlapped with aregion where the fourth through hole 50 ct is formed, and the fourthbump electrode 50 bp may be connected to the fourth pad 50 pd throughthe fourth through hole 50 ct. The first, second, third, and fourth bumpelectrodes 20 bp, 30 bp, 40 bp, and 50 bp may be formed by depositing aconductive layer on the substrate 11 and patterning the conductivelayer. The conductive layer may include at least one of, for example, NiAg, Au, Pt, Ti, Al, Cr, Wi, TiW, Mo, Cu, TiCu, and the like.

Referring back to FIGS. 1B through 1D, the first, second, third, andfourth connection electrodes 20 ce, 30 ce, 40 ce, and 50 ce spaced apartfrom one another are formed on the light emitting stacked structure. Thefirst, second, third, and fourth connection electrodes 20 ce, 30 ce, 40ce, and 50 ce are electrically connected to the first, second, third,and fourth bump electrodes 20 bp, 30 bp, 40 bp, and 50 bp, respectively,thereby providing a path for a transmission of an external signal toeach of the light emitting stacks 20, 30, and 40. More specifically,according to the illustrated exemplary embodiment, the first connectionelectrode 20 ce is connected to the first bump electrode 20 bp connectedto the first upper contact electrode 21 n through the first pad 20 pd,so that the first connection electrode 20 ce may be electricallyconnected to the first conductivity type semiconductor layer 21 of thefirst light emitting stack 20. The second connection electrode 30 ce isconnected to the second bump electrode 30 bp connected to the second pad30 pd, so that the second connection electrode 30 ce may be electricallyconnected to the first conductivity type semiconductor layer 31 of thesecond light emitting stack 30. The third connection electrode 40 ce isconnected to the third bump electrode 40 bp connected to the third pad40 pd, so that the third connection electrode 40 ce may be electricallyconnected to the first conductivity type semiconductor layer 41 of thethird light emitting stack 40. The fourth connection electrode 50 ce isconnected to the fourth bump electrode 50 bp connected to the fourth pad50 pd, so that the fourth connection electrode 50 ce may be electricallyconnected to the second conductivity type semiconductor layers 25, 35,and 45 of the light emitting stacks 20, 30, and 40 through the first,second and third lower contact electrodes 25 p, 35 p, and 45 p,respectively.

The method of forming the first, second, third, and fourth connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce is not particularly limited.For example, according to an exemplary embodiment, a seed layer may bedeposited as a conductive surface on the light emitting stackedstructure, and the seed layer may be patterned using photolithography orthe like, such that the seed layer is disposed at a desired locationwhere the connection electrode is to be formed. According to anexemplary embodiment, the seed layer may be deposited to have athickness of about 1000 Å, but the inventive concepts are not limitedthereto. Subsequently, the seed layer may be plated with metal, such asCu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag or an alloy thereof, and thephotoresist pattern and the seed layer may be removed. In some exemplaryembodiments, to prevent or at least inhibit oxidation of the platedmetal, an additional metal may be deposited or plated with electrolessnickel immersion gold (ENIG) or the like on the plated metal (forexample, connection electrodes). In some exemplary embodiments, the seedlayer may be retained on each of the connection electrodes.

According to an exemplary embodiment, when the bump electrodes 20 bp, 30bp, 40 bp, and 50 bp are omitted from contacts 20C, 30C, 40C, and 50C,the pads 20 pd, 30 pd, 40 pd, and 50 pd may be connected to therespective connection electrodes 20 ce, 30 ce, 40 ce, and 50 ce. Forexample, after the through holes 20 ct, 30 ct, 40 ct, and 50 ct areformed to partially expose the pads 20 pd, 30 pd, 40 pd, and 50 pd ofthe contacts 20C, 30C, 40C, and 50C, the seed layer may be deposited onthe light emitting stacked structure as a conductive surface, and theseed layer may be patterned using photolithography or the like so thatthe seed layer is disposed at a desired location where the connectionelectrode is to be formed. In this case, the seed layer may beoverlapped with at least a portion of each of the pad 20 pd, 30 pd, 40pd, and 50 pd. According to an exemplary embodiment, the seed layer maybe deposited to have a thickness of about 1000 Å, but the inventiveconcepts are not limited thereto. Thereafter, the seed layer may beplated with metal, such as Cu, Ni, Ti, Sb, Zn, Mo, Co, or the like, andthe seed layer may be removed. In some exemplary embodiments, to preventor at least inhibit oxidation of the plated metal, an additional metalmay be deposited or plated with ENIG or the like on the plated metal(for example, connection electrodes). In some exemplary embodiments, theseed layer may be retained on each of the connection electrodes.

According to the illustrated exemplary embodiment, each of theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce may have asubstantially elongated shape to be spaced apart from the substrate 11.In another exemplary embodiment, the connection electrodes 20 ce, 30 ce,and 40 ce may include two or more metals or a plurality of differentmetal layers to reduce stress from the elongated shape of the connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce. However, the inventiveconcepts are not limited to a specific shape of the connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce, and, in some exemplaryembodiments, the connection electrode may have various shapes.

As shown in the drawings, each of the connection electrodes 20 ce, 30ce, 40 ce, and 50 ce may have a substantially flat upper surface tofacilitate electrical connection between the light emitting stackedstructure and outer lines or electrodes. The connection electrodes 20ce, 30 ce, 40 ce, and 50 ce may be overlapped with at least one stepformed on the side surface of the light emitting stacked structure. Inthis manner, a lower surface of the connection electrode may provide alarger contact area than that of an upper surface thereof, therebyproviding a larger contact area between the connection electrodes 20 ce,30 ce, 40 ce and 50 ce and the light emitting stacked structure. In thismanner, the light emitting device 100 along with a protection layer 90may have a more stable structure that is capable of withstanding varioussubsequent processes. In this case, a length L of one side surface ofthe connection electrodes 20 ce, 30 ce, 40 ce, and 50 ce that faces tothe outside and a length L′ of another surface that faces a center ofthe light emitting device 100 may be different. For example, adifference in lengths between two surfaces of the connection electrodeopposite to each other may be about 3 μm to about 16 μm, but theinventive concepts are not limited thereto.

Then, the protection layer 90 is disposed between the connectionelectrodes 20 ce, 30 ce, 40 ce, and 50 ce. The protection layer 90 maybe formed to be substantially flush with the upper surfaces of theconnection electrodes 20 ce, 30 ce, 40 ce, and 50 ce by a polishingprocess or the like. According to an exemplary embodiment, theprotection layer 90 may include a black epoxy molding compound (EMC),but the inventive concepts are not limited thereto. For example, in someexemplary embodiments, the protection layer 90 may include aphotosensitive polyimide dry film (PID). In this manner, the protectionlayer 90 may provide a sufficient contact area to the light emittingdevice 100 not only to protect the light emitting structure fromexternal impacts that may be applied during subsequent processes, butalso to facilitate handling during a subsequent transferring step. Inaddition, the protection layer 90 may prevent light leakage from theside surface of the light emitting device 100 to prevent or at least tosuppress interference of light emitted from adjacent light emittingdevices 100.

FIG. 10 exemplarily shows a plurality of light emitting devices 100disposed on the substrate 11, and a singularizing process is applied toseparate each of the light emitting devices 100. Referring to FIG. 11,according to an exemplary embodiment, laser beams may be irradiatedbetween the light emitting stacked structures to form a separation paththat partially separates the light emitting stacked structures.Referring to FIG. 12, a first bonding layer 95 is attached to thesubstrate 11, and the substrate 11 with the first bonding layer 95attached thereon may be cut or broken using various methods that arewell known in the art to unify each of the light emitting devices 100.For example, the substrate 11 may be cut by dicing the substrate 11through a scribing line formed thereon, or the substrate 11 may bebroken by applying a mechanical force along the separation path formedduring a laser radiation process. The first bonding layer 95 may be atape, but the inventive concepts are not limited thereto, as long as thefirst bonding layer 95 may stably attach the light emitting device 100while separating the light emitting devices 100 in a subsequent process.Although the first bonding layer 95 has been described above as beingattached on the substrate 11 after the laser radiation step, in someexemplary embodiments, the first bonding layer 95 may be attached on thesubstrate 11 before the laser radiation step.

FIGS. 14, 15, 16, and 17 are cross-sectional views schematicallyillustrating a process of manufacturing a light emitting packageaccording to an exemplary embodiment. The light emitting device 100according to an exemplary embodiment may be transferred and packaged invarious ways known in the art. Hereinafter, a second adhesive layer 13will be exemplarily illustrated as being attached to the substrate 11using a carrier substrate 11 c to transfer the light emitting device100. However, the inventive concepts are not limited to a specifictransfer method.

Referring to FIG. 14, according to an exemplary embodiment, thesingularized light emitting device 100 may be transferred to the carriersubstrate 11 c with the second adhesive layer 13 interposedtherebetween. In this case, when the light emitting device 100 includesconnection electrodes protruding outwardly from the light emittingstacked structure, various problems may occur in subsequent processes,particularly in a transfer process, due to their non-uniformed structureas described above. In addition, when the light emitting device 100includes micro-LEDs having a surface area of about 10,000 μm² or less,of about 4,000 μm² or less, or about 2,500 μm² or less, depending on theapplication, handling of the light emitting device may be more difficultdue to its small form factor. However, according to an exemplaryembodiment, since the light emitting device 100 is provided with theprotection layer 90 disposed between the connection electrodes 20 ce, 30ce, 40 ce, and 50 ce, handling of the light emitting device 100 may befacilitated during subsequent processes, such as transfer and packaging.In addition, the light emitting structure may be protected from externalimpact, and interference of light between adjacent light emittingdevices 100 may be prevented by the protection layer 90.

The carrier substrate 11 c is not particularly limited as long as thecarrier substrate 11 c stably mounts the light emitting device 100thereon with the second adhesive layer 13. The second adhesive layer 13may be a tape, but the inventive concepts are not limited thereto, aslong as the second adhesive layer 13 stably attaches the light emittingdevice 100 to the carrier substrate 11 c, and the light emitting device100 is capable of being separated during subsequent processes. In someexemplary embodiments, the light emitting device 100 of FIG. 13 may notbe transferred to the separate carrier substrate 11 c, but may bedirectly transferred to a circuit board 11 p. In this case, the carriersubstrate 11 c illustrated in FIG. 14 may be the substrate 11, and thesecond adhesive layer 13 illustrated in FIG. 14 may be the first bondinglayer illustrated in FIG. 13.

The light emitting device 100 may be mounted on the circuit board 11 p.According to an exemplary embodiment, the circuit board 11 p may includean upper circuit electrode 11 pa, a lower circuit electrode 11 pc, andan intermediate circuit electrode 11 pb that are electrically connectedto one another. The upper circuit electrodes 11 pa may correspond toeach of the first, second, third, and fourth connection electrodes 20ce, 30 ce, 40 ce, and 50 ce, respectively. In some exemplaryembodiments, the upper circuit electrodes 11 pa may be surface-treatedby ENIG, and be partially melt at a high temperature, therebyfacilitating electrical connection to the connection electrodes of thelight emitting device 100.

According to the illustrated exemplary embodiment, the light emittingdevices 100 may be spaced apart from one another on the carriersubstrate 11 c at a desired pitch in consideration of a pitch P (seeFIG. 16B) of the upper circuit electrode of the circuit board 11 p,which will be mounted on a final target device such as a displayapparatus.

According to an exemplary embodiment, the first, second, third, andfourth connection electrodes 20 ce, 30 ce, 40 ce, and 50 ce of the lightemitting device 100 may be bonded to the upper circuit electrodes 11 paof the circuit board 11 p, respectively, by anisotropic conductive film(ACF) bonding, for example. When the light emitting device 100 is bondedto the circuit board 11 p through ACF bonding, which may be performed ata lower temperature than other bonding methods, the light emittingdevice 100 may be prevented from being exposed to a high temperaturewhile bonding. However, the inventive concepts are not limited to aspecific bonding method. For example, in some exemplary embodiments, thelight emitting devices 100 may be bonded to the circuit board 11 p usinganisotropic conductive paste (ACP), solder, a ball grid array (BGA), ora micro bump including at least one of Cu and Sn. In this case, sincethe upper surfaces of the connection electrodes 20 ce, 30 ce, 40 ce, and50 ce and the protection layer 90 are substantially flush with oneanother by a polishing process or the like, adhesion of the lightemitting device 100 to the anisotropic conductive film increases, andthus a more stable structure may be formed when bonded to the circuitboard 11 p.

Referring to FIG. 15, a molding layer 91 is formed between the lightemitting devices 100. According to an exemplary embodiment, the moldinglayer 91 may transmit a portion of light emitted from the light emittingdevice 100, and may reflect, diffract, and/or absorb a portion ofexternal light so as to prevent external light from being reflected bythe light emitting device 100 in a direction visible to the user. Themolding layer 91 may cover at least a portion of the light emittingdevice 100 to protect the light emitting device from moisture andstress. In addition, the molding layer 91, along with the protectionlayer 90 formed on the light emitting device 100, may enhance thestructure thereof to provide additional protection to the light emittingpackage.

According to an exemplary embodiment, when the molding layer 91 coversan upper surface of the substrate 11 facing the circuit board 11 p, themolding layer 91 may have a thickness of less than about 100 μm totransmit at least 50% of light. In an exemplary embodiment, the moldinglayer 91 may include an organic or inorganic polymer. In some exemplaryembodiments, the molding layer 91 may further include fillers such assilica or alumina. In some exemplary embodiments, the molding layer 91may include substantially the same material as the protection layer 90.The molding layer 91 may be formed through various methods known in theart, such as lamination, plating and/or printing methods. For example,the molding layer 91 may be formed by a vacuum lamination process, inwhich an organic polymer sheet is disposed on the light emitting device100 and subjected to a high temperature and a high pressure in vacuum,and thus, a substantially flat upper surface of the light emittingpackage may be provided, thereby improving uniformity of light.

In some exemplary embodiments, the substrate 11 may be removed from thelight emitting device 100 before the molding layer 91 is formed. Whenthe substrate 11 is a patterned sapphire substrate, an irregularityportion may be formed on the first conductivity type semiconductor layer41 of the third light emitting stack 40 that is in contact with thesubstrate 11, thereby improving luminous efficiency. In anotherexemplary embodiment, irregularities may be formed on the firstconductivity type semiconductor layer 41 of the third light emittingstack 40 by etching or patterning after the first conductivity typesemiconductor layer 41 of the third light emitting stack 40 is separatedfrom the substrate 11

Referring to FIGS. 16A and 16B, the light emitting device 100 disposedon the circuit board 11 p may be cut into a desired configuration andformed as a light emitting package 110. FIG. 16B exemplarily illustratesfour light emitting devices 100 (2×2) disposed on the circuit board 11p. However, the inventive concepts are not limited to a specific numberof light emitting devices formed in the light emitting package 110. Forexample, in some exemplary embodiments, the light emitting package 110may include one or more light emitting devices 100 formed on the circuitboard 11 p. In addition, the inventive concepts are not limited to aspecific arrangement of one or more light emitting devices 100 in thelight emitting package 110. For example, in some exemplary embodiments,one or more light emitting devices 100 may be arranged in the lightemitting package 110 in an n×m-arrangement, in which n and m are naturalnumbers. According to an exemplary embodiment, the circuit board 11 pmay include a scan line and a data line to independently drive each ofthe light emitting devices 100 included in the light emitting package110.

Referring to FIG. 17, a light emitting package 110 may be mounted on atarget substrate 11 b of a final apparatus, such as a display apparatus.The target substrate 11 b may include target electrodes 11 s thatcorrespond to lower circuit electrodes 11 pc of the light emittingpackage 110, respectively. The display apparatus according to anexemplary embodiment may include a plurality of pixels, and each of thelight emitting devices 100 may be disposed corresponding to each of thepixels. More specifically, each light emitting stack of the lightemitting devices 100 according to an exemplary embodiment may correspondto each sub-pixel of one pixel. Since the light emitting devices 100include the light emitting stacks 20, 30, and 40 that are verticallystacked, the number of devices to be transferred for each sub-pixel maybe substantially reduced than that of conventional light emittingdevices. In addition, since surfaces of connection electrodes oppositeto each other have different lengths from each other, the connectionelectrode may be stably formed in the light emitting stacked structureto enhance an internal structure thereof. In addition, since the lightemitting devices 100 may include a protection layer 90 between theconnection electrodes, the light emitting devices 100 may be protectedfrom an external impact.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A light emitting device for a display,comprising: a first LED sub-unit; a second LED sub-unit disposed on thefirst LED sub-unit; and a third LED sub-unit disposed on the second LEDsub-unit, wherein the third LED sub-unit is configured to emit lighthaving a shorter wavelength than that of light emitted from the firstLED sub-unit, and to emit light having a longer wavelength than that oflight emitted from the second LED sub-unit.
 2. The light emitting devicefor a display of claim 1, wherein the first, second, and third LEDsub-units are configured to emit red light, blue light, and green light,respectively.
 3. The light emitting device for a display of claim 1,wherein: the first LED sub-unit includes a first light emitting stack;the second LED sub-unit includes a second light emitting stack; thethird LED sub-unit includes a third light emitting stack; and each ofthe light emitting stacks includes a first conductivity typesemiconductor layer, an active layer, and a second conductivity typesemiconductor layer.
 4. The light emitting device for a display of claim3, further comprising a substrate on which the first, second, and thirdLED sub-units are disposed, wherein: the third LED sub-unit is disposedcloser to the substrate than the first and second LED sub-units; and thesubstrate has irregularities on an upper surface thereof.
 5. The lightemitting device for a display of claim 4, wherein the substratecomprises a patterned sapphire substrate.
 6. The light emitting devicefor a display of claim 4, wherein the first conductivity typesemiconductor layer of the third LED stack is in contact with the uppersurface of the substrate.
 7. The light emitting device for a display ofclaim 1, further comprising: a first bonding layer interposed betweenthe first LED sub-unit and the second LED sub-unit; and a second bondinglayer interposed between the second LED sub-unit and the third LEDsub-unit.
 8. The light emitting device for a display of claim 7, furthercomprising a first connection electrode overlapping with at least one ofthe first, second, and third LED sub-units and electrically connected toat least one of the first, second, and third LED sub-units, wherein: thefirst connection electrode has a first side surface of a first lengthand a second side surface of a second length and opposing the first sidesurface; and a difference between the first length and the second lengthis greater than a thickness of at least one of the LED sub-units.
 9. Thelight emitting device for a display of claim 8, further comprising aprotection layer surrounding at least a portion of the first connectionelectrode and exposing a side surface of the substrate.
 10. The lightemitting device for a display of claim 8, wherein the first side surfacefaces the outside of the light emitting device, the second side surfacefaces a center of the light emitting device, and the first length of thefirst side surface is greater than the second length of the second sidesurface.
 11. The light emitting device for a display of claim 9,wherein: the protection layer includes an epoxy molding compound orpolyimide film; and the protection layer covers an upper surface of thefirst LED sub-unit.
 12. The light emitting device for a display of claim8, further comprising: a second connection electrode electricallyconnected to the first LED sub-unit; a third connection electrodeelectrically connected to the second LED sub-unit; and a fourthconnection electrode electrically connected to the third LED sub-unit,wherein the first connection electrode is electrically connected to eachof the first, second, and third LED sub-units.
 13. The light emittingdevice for a display of claim 12, wherein the lower surfaces of thefirst, second, third, and fourth connection electrodes are larger thanthe respective upper surfaces.
 14. The light emitting device for adisplay of claim 12, wherein at least one of the first, second, third,and fourth connection electrodes overlaps a side surface of each of thefirst, second, third, and fourth LED sub-units.
 15. The light emittingdevice for a display of claim 1, wherein: the first LED sub-unitincludes a first conductivity type semiconductor layer, an active layer,a second conductivity type semiconductor layer, and an upper contactelectrode in ohmic contact with the first conductivity typesemiconductor layer, the first conductivity type semiconductor layerincludes a recessed portion; and the upper contact electrode is formedin the recessed portion of the first conductivity type semiconductorlayer.
 16. A light emitting package, comprising: a circuit board; alight emitting device disposed on the circuit board; and a molding layercovering the light emitting device, wherein the light emitting devicecomprises: a first LED sub-unit; a second LED sub-unit disposed on thefirst LED sub-unit; and a third LED sub-unit disposed on the second LEDsub-unit, and wherein the third LED sub-unit is configured to emit lighthaving a shorter wavelength than that of light emitted from the firstLED sub-unit, and to emit light having a longer wavelength than that oflight emitted from the second LED sub-unit.
 17. The light emittingpackage of claim 16, wherein: the light emitting device furthercomprises a substrate; the third LED sub-unit is disposed closer to thesubstrate than the first and second LED sub-units; and the substrate hasirregularities on an upper surface thereof.
 18. The light emittingpackage of claim 16, wherein: the light emitting device furthercomprises a plurality of connection electrodes disposed on the first,second, and third LED sub-units, and a protection layer disposed betweenthe connection electrodes; and the protection layer and the moldinglayer include different materials from each other.
 19. The lightemitting package of claim 16, wherein: the first LED sub-unit includes afirst conductivity type semiconductor layer, an active layer, a secondconductivity type semiconductor layer, and an upper contact electrode inohmic contact with the first conductivity type semiconductor layer; thefirst conductivity type semiconductor layer includes a recessed portion;and the upper contact electrode is formed in the recessed portion of thefirst conductivity type semiconductor layer.
 20. The light emittingpackage of claim 16, wherein: at least one of the connection electrodeshas a first side surface with a first length and a second side surfacewith a second length and opposing the first side surface; and adifference between the first length and second length is at least 3 μm.